First make the sour cream sauce by placing all the ingredients in a small bowl. Stir well and set aside or chill until needed. Preheat the oven to 425F. In a large bowl, combine all the ingredients for the meatballs except the sunflower oil. Mix with your hands and then shape into about 18 burgers, each weighing about 1 1/2 oz. Pour enough sunflower oil into a large frying pan to form a layer about 1/16” thick on the pan bottom. Heat over medium heat until hot, then sear the meatballs in batches on all sides. Cook each batch for about 4 minutes, adding oil as needed, until golden brown. Carefully transfer the seared meatballs to a baking sheet lined with waxed paper and place in the oven for 5 to 7 minutes, or until just cooked through. Serve warm or at room temperature, with the sauce spooned over or on the side.